1
a
: any of numerous mechanical devices by which the flow of liquid, gas, or loose material in bulk may be started, stopped, or regulated by a movable part that opens, shuts, or partially obstructs one or more ports or passageways
also
: the movable part of such a device
b
: a device in a brass instrument for quickly channeling air flow through an added length of tube in order to change the fundamental tone by some definite interval
c
chiefly British
: electron tube
2
[borrowed from Medieval Latin valva, going back to Latin]
: a bodily structure (such as the mitral valve) that closes temporarily a passage or orifice or permits movement of fluid in one direction only
3
[borrowed from New Latin valva, going back to Latin]
: one of the distinct usually hinged and movable pieces of which the shell of some shell-bearing animals (such as lamellibranch mollusks, brachiopods, and barnacles) consists
4
[borrowed from New Latin valva, going back to Latin]
a
: one of the segments or pieces into which a dehiscing capsule or legume separates
b
: the portion of various anthers (as of the barberry) resembling a lid
c
: one of the two encasing membranes of a diatom
5
archaic
: a leaf of a folding or double door
Cite this Entry
“Valve.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/valve. Accessed 1 Sep. 2026.
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